Preamp tubes fill many roles in various equipments. Preamp tubes take small signal from sources such as guitar pickup, phono cartridge, and even DAC output, and amplify the signal to feed into power amp stage. Preamp tubes are also used to create push-pull signal to drive the output power tubes. In some equipment, the same preamp tubes are used as buffers with little gain to drive line level output in DA converter, or headphones.

Since the requirement for preamp tube can vary greatly, it's important you know how to pick right preamp tube for your amp.

High Gain Preamp Tubes

The first stage of guitar amps (often called V1) or audio amps usually amplifies the signal the most. This means it has the most effect on the sonic quality. It also means noise from the tube - both white electric and mechanical - will be more noticeable.

For these first stage applications, it's best to pick tubes that are low in noise. There are mostly two types of noise from tube amps. One is white noise. This is usually caused by stray ions left inside the vacuum tubes. Another type of noise is microphonics. This type of noise is caused by electrodes physically picking up vibrations.

All tubes have both types of noise, but to a varying degree. In most cases, a regular tube with average noise will work fine, but if noise matters, we offer lose noise screening where we carefully listen to each tube in special test equipment to select lowest noise tube.

Triode Matching

Many small signal tubes (
12AX7, 12AT7, 12AU7 and 6DJ8/6922 to name a few) are dual triode tubes. These tubes actually contain two triodes. Many amps use the two triodes to drive power tube paris, or use them across two channels.

Now, most amp circuits are designed such that it can absorb variances in tubes including dual triodes. So regular tubes will work fine in most cases, but some differences will remain. Getting triode matched tubes will ensure ensure everything is balanced and in order. We offer triode matching as an option in such case. In addition, matched preamp tube pairs offered by us matches all the triode on all the tubes.